1. Field of the Invention
The present invention relates to computer security systems used to prevent unauthorized access to the computer's operating system by peripheral input devices such as a keyboard or mouse via the keyboard controller.
2. Description of the Related Art
Security systems of various kinds are well known in the art for computer systems and computer related applications. These security systems have been designed to safeguard sensitive information which may be stored or processed within computer systems and to prevent unauthorized access to the computer's operating system. The desirability for computer security systems has increased significantly over recent years with the proliferation of personal and business computer systems and with the storage of increasingly valuable and/or classified information within these computer systems. Additionally, computer viruses have become more prevalent, increasing the need to prevent unauthorized access to the operating system of the computer.
In computer systems such as the PC and AT compatible systems, little or no security was initially provided. Security needs are now given higher priority. Thus, computer systems such as the PS/2 were designed to incorporate security features. For example, in one prior computer security system, a user enters a password during boot operations in order to gain access to information within the computer system. In another previous computer security system, a user is able to lock the keyboard through a designated series of keystrokes. The user can then regain access to the computer system by entering the correct password on the keyboard. In yet another computer security system, the keyboard automatically locks after the keyboard remains inactive over a preset interval. After the keyboard locks, when a key is pressed, the user is prompted to enter a password. Once the user enters a correct password, the keyboard becomes fully active, and operation of the computer system begins where it stopped. These security systems are generally operated by the host operating system.
The demand for increased computer security has become even more urgent with the advent of computer viruses which can enter a computer system by a variety of different channels. Many viruses are even capable of entering a computer system and disabling the security system. This poses a significant problem with terminate-and-stay-resident (TSR) computer security systems operating in the host computer. Because the operating system (OS) executes TSR programs, a virus which enters the OS from the hard drive, a modem or other input device could easily disable these security systems. An unauthorized user could then obtain access to the computer. Furthermore, since this type of security system is contained solely in software, users could potentially access this software and disable the security system without the proper password. Thus, a need exists for a computer security system that provides a safeguard against unauthorized access to the operating by means of the keyboard or mouse or otherwise and that is less susceptible to computer by viruses or other tampering.